The kettlebell, which dates back to the late 1800s, was reintroduced to the U.S. fitness landscape in the early 2000s, going from an obscure training tool rarely seen in commercial health clubs to being widely available in sporting-goods stores and utilized by trainers and group fitness instructors alike. And for good reason—the kettlebell can be used to perform a number of different exercises and has been shown to be effective and efficient in eliciting improvements in both strength and cardiovascular fitness.

The two-handed kettlebell swing is a great example of the type of dynamic exercises that can be accomplished using this unique piece of equipment. However, as is the case with all dynamic exercises, proper form is absolutely essential for reducing one’s risk of injury. If you’re considering introducing kettlebell swings into your clients’ strength-training programs, here is a comprehensive guide to its benefits, primary movement pattern and major muscles involved, proper form and essential tips for beginners.

Primary Movement Pattern

There are two versions of the kettlebell swing. While one version includes a squat during the lowering phase of the weight, the original version taught by the Soviets involves performing a hip hinge with the feet parallel to one another. This second version is featured here.

Executing the swing with a hip hinge requires the spine to remain long and straight as the exerciser pushes the hips back to create the forward lean of the torso. During the forward-hinging movement, the chest lowers to the floor as a result of flexion at the hips, which lengthens the muscles responsible for creating hip extension. In the hip hinge, the knees remain in a slightly flexed position with the shins relatively vertical to the floor. When performed correctly, the swing is executed from the hips with minimal movement from the knees.

Major Muscles Involved

The prime movers of the kettlebell swing are the posterior-chain muscles responsible for creating closed-chain hip extension; specifically, the hamstrings (semitendonosus, semimembranosus and biceps femoris), gluteus maximus and adductor magnus. Additionally, the flexor muscles of the forearm (brachioradialis and flexor digitorum) are responsible for establishing grip strength, while the latissimus dorsi and triceps are responsible for shoulder extension.

The synergists of the kettlebell swing are the muscles responsible for closed-chain knee extension; specifically, the quadriceps (rectus femoris, vastus lateralis, vastus intermedius and vastus medialis), gastrocnemius and hamstrings (in a closed-chain position, both the calf and hamstring muscles can assist with knee extension). Additionally, the deep abdominal stabilizers (thoracolumbar fascia, the transversus abdominis, the lumbar multifidii and posterior fibers of the internal oblique) help maintain intersegmental stability of the spine, while the anterior deltoids and biceps brachii are responsible for shoulder flexion.

Benefits of the Kettlebell Swing

Traditional free weights like barbells and dumbbells are gripped between two equal amounts of mass—the grip point is the center of mass for the entire weight. By contrast, the handle of a kettlebell is outside the center of mass, which requires the exerciser to exert more muscle force to control the movement of the weight, especially during the swing exercise.

The kettlebell swing requires a lifter to exert more force from the hip extensor muscles to overcome gravity and generate the upward trajectory. As the kettlebell transitions to the downward phase, gravity accelerates the mass, which creates additional momentum and challenges the lifter to apply high levels of muscle force to decelerate and control the movement. When performed correctly, the kettlebell swing provides a variety of physiological benefits, making it an extremely efficient exercise for helping clients achieve a number of fitness goals with one easy-to-learn move.

Many personal trainers will testify to the power of kettlebells to help clients see results. Artemis Scantalides, for example, is a StrongFirst Level II and Russian Kettlebell Challenge (RKC) Level II kettlebell instructor and co-owner of the Iron Body Studios in Boston, which specializes in kettlebell training. Scantalides is a huge fan of the kettlebell swing, because “[it] trains the body to maintain a stiff and stable spine while managing an unstable load.”

There is more than anecdotal evidence, however, to support the benefits of using kettlebells. Over the past decade or so, a growing body of research has helped to quantify the benefits of kettlebell training. Lake and Lauder, for example, found that the significant mechanical demand of the kettlebell swing “is sufficient to increase both maximum and explosive strength,” which makes it a particularly “useful addition to strength and conditioning programs that aim to develop the ability to rapidly apply force” (Lake and Lauder, 2012a; 2012b).

Furthermore, due to it’s basic movement pattern of hip flexion and extension, the kettlebell swing has also been shown to help strengthen the posterior chain muscles responsible for hip extension, while also strengthening the deep core muscles that provide spinal stabilization (Budnar et al., 2014).

Additional studies have shown that the kettlebell swing is an effective exercise for improving aerobic efficiency, enhancing power output of the hips extensors as well as elevating levels of the hormones that promote muscle growth. Farrar, Mayhew and Koch (2010), for example, found that a common kettlebell workout that challenges participants to complete as many two-handed swings as possible in 12 minutes created a metabolic challenge sufficient to improve overall aerobic capacity. In a similarly designed study, Budnar and associates (2014) found that a workout featuring kettlebell swings performed for a 30-second period of work followed by a 30-second rest interval for 12 minutes helped elevate levels of testosterone and growth hormone, both of which are important for promoting protein synthesis and increasing muscle size.

Finally, an ACE-sponsored research study found that participants following a standard kettlebell-training protocol can burn upwards of 20 calories per minute, which makes this modality an extremely time-efficient way to exercise (Schettler et al., 2010).

Functional Benefits

Because it improves hip mobility, strength and power, the kettlebell swing can help clients achieve success in a wide range of daily activities, such as carrying kids, loading and unloading a car, carrying objects up and down stairs, and a variety of household tasks involving bending and lifting. Scantalides uses the swing as a foundational movement in her clients’ programs. “It’s a strength, core and cardiovascular exercise, all combined into one movement.” In fact, she says, “the kettlebell swing can be considered a ballistic version of the plank, because it can strengthen the entire posterior chain along with the core muscles responsible for optimal spinal stability.”

Jen Sinkler, a former member of the USA National Women’s Rugby team, strength coach and creator of the ‘Lift Weights Faster, Parts 1 and 2’ workout program is also a huge proponent of the kettlebell swing. “The ballistic, eccentric phase of the lift (when the kettlebell is lowering back under the lifter) trains the ability to rapidly load a mechanical force in the muscle tissue,” she explains, “which is an extremely important skill to have.”

Step-by-Step How-to

Stand with feet shoulder-width apart and knees slightly bent. Place a kettlebell on the floor between the feet.

Keep the spine long and hinge forward at the hips to lean down and grip the kettlebell with both hands in a palms-down grip. (Tip: Squeeze the handle in both hands to maintain a firm grip during the exercise.)

Keep the shins vertical to the floor and the spine straight as you pull the kettlebell back between the legs.

Quickly push the hips forward and pull the knees back to generate the forward momentum to swing the kettlebell forward and up in front of the body. The strength to move the weight should come from the legs and hips, NOT the shoulders.

The explosive extension of the hips should propel the kettlebell up to chest or shoulder height. (Tip: Inhale as the kettlebell is elevating and you are in a standing position.)

As the kettlebell reaches the top of the move, brace the abdominal muscles and contract the arm and shoulder muscles to create a brief pause before pulling the kettlebell back down between the legs for the next repetition. (Tip: Exhale as you bring the kettlebell back down and hinge forward at your hips.)

It is important to note that a successful swing maintains muscle tension in the legs and core, which helps to generate mechanical energy from the elastic fascia and connective tissue. The rapid downward movement of the weight combined with the quick forward flexion at the hips allows the elastic fascia and connective tissue of the posterior chain muscles to lengthen and store mechanical energy, which is then released when the hips snap forward to initiate the upward movement of the swing.

The kettlebell swing can either be performed for a specific number of repetitions or a predetermined amount of time. If a client’s goal is to improve muscle power output, use a heavier kettlebell and limit the number of repetitions to eight or fewer with an emphasis on exploding the hips forward during the upward phase of the swing. If a client’s goal is to improve aerobic conditioning, use a countdown timer set for 30 seconds of work and 30 seconds for recovery. Be sure to select a weight that allows the client to maintain good form throughout the duration of the work interval.

Teaching the Lift

The first step in teaching the kettlebell swing is educating a client on how to perform a proper hip hinge. Some clients may only take a few repetitions to learn the movement, while other clients may require a few sessions to develop an efficient hip-hinge pattern. To help reinforce the motor learning and develop strength in the posterior chain, incorporate movements such as the glute bridge and standing hip hinge into a client’s dynamic warm-up at the start of his or her workout session.

Once the client can successfully execute a hip hinge, introduce external resistance by having the client hold a kettlebell to perform the movement. Here’s a general guideline to follow: Once a client can successfully perform a loaded hip hinge with a kettlebell and maintain good form for approximately 12 to 15 repetitions, he or she is ready to progress to ballistic swings.

Common Mistakes

A common mistake often made by people learning the swing is to do a squat instead of a hip hinge. Simply hinging forward at the hips to create hip flexion is extremely effective at engaging the posterior muscles responsible for producing hip extension. Sinkler reminds clients that the kettlebell swing is a horizontal movement, so the goal is to move forward and backward by flexing and extending the hips, rather than the lowering and raising movement of a squat.

Another common mistake is to think about lifting the kettlebell with the arms and shoulders as you would in a front (anterior deltoid) raise, rather than generating the momentum to move the weight from an explosive hip extension. To help her clients learn how to properly use their hips to lift the kettlebell, Sinkler encourages them to drive their hips forward and to think about the explosive movement of the hips as allowing the kettlebell to “float” up to shoulder height.

Tips for Beginners

To help learn the movement and groove the pattern, encourage clients to push their heels into the floor and, as the kettlebell rises into the upward phase of the movement, to think about pulling the bottom of the pelvis to the back of the thighs.

On the down phase of the swing, coach clients to push their hips back and visualize that they are “hiking” (as a center would hike a football) the kettlebell back between their legs. This is a great visual-kinesthetic cue—the client doesn’t need experience actually playing football to understand the purpose of the action.

To help clients develop a vise-like grip on the kettlebell, Scantalides coaches clients to “break the handle” and visualize pulling the handle of the kettlebell apart with both hands. She also helps clients develop the right amount of upper-body tension by instructing them to contract their lats, lower back and shoulder muscles before starting a set of swings.

Conclusion

Given their wide ranging benefits and effectiveness, kettlebells will likely continue to increase in popularity. If you haven’t yet started using kettlebells with your clients, the two-handed swing is an easy-to-learn exercise movement that can help them achieve results in a relatively short amount of time.

References

Beardsley, C. and Contreras, B. (2014). The role of kettlebells in strength and conditioning: A review of the literature. Strength and Conditioning Journal, 36, 3, 64-70.

Author

Pete McCall

Health and Fitness Expert

Pete McCall, MS, CSCS, is an ACE Certified Personal Trainer and long-time player in the fitness industry. He has been featured as an expert in the Washington Post, The New York Times, Los Angeles Times, Runner's World and Self. He holds a master's degree in exercise science and health promotion, and several advanced certifications and specializations with NSCA and NASM.